Fault current with zero-frequency quantity can arise in case of earth contact in frequency inverter.
Therefore the leakage current of the Y capacitors make use of protective equipment against standard fault current (FI) (pulsating current sensitive) impossible.
The operation manual shall inform that use of protective fault current equipment only does not fulfill the requirements of VDE 0160, chapter 5.2.11.2: April 1998.

Все три предложения повергают в недоумение, особенно:
zero-frequency quantity
earth contact in frequency inverter
pulsating current sensitive
...use of protective fault current equipment only does not fulfill... (???)

Помогите, пожалуйста!